It's a real estate agency, so it's almost a household. The ringing is silent for most of the extensions. But the owner wants this to be done this way and I have to find a solution to the problem.

As the TDA30 is full, all extensions used. The next step for him is to upgrade to TDA100 or some VoIP solution. If he upgrades to TDA100 I have to solve this anyway, as the ICD groups of the TDA100 only holds 32 members.